If you are going to inform all of your old flickr friends about your new ipernity account, you can do it like this:
- get Mozilla/Firefox
- install Greasemonkey
addons.mozilla.org/en-US/firefox/addon/748
- install flickr-multimailer Greasemonkey script by clicking the following link:
www.flickr.com/help/forum/34561/?search=multimailer
- go to flickrmail / compose new message:
www.flickr.com/messages_write.gne
Click on the new link "Enable Multiple Recipients" in the "To:" field and select a number of recipients, write your message, send and lean back :-)
[EDIT]
If, for whatever reason, you are unable to use the described approach - maybe an easy solution would be to do this from the computer of a friend who's already got all that stuff installed. Just sign in at flickr, send your mail and sign out again.